Define a LoggingSettings struct to use for InitLogging()

base/logging.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_LOGGING_H_
 #define BASE_LOGGING_H_
 
 #include <cassert>
 #include <string>
 #include <cstring>
@@ skipping 128 matching lines @@
 //
 // Note the special severity of ERROR_REPORT only available/relevant in normal
 // mode, which displays error dialog without terminating the program. There is
 // no error dialog for severity ERROR or below in normal mode.
 //
 // There is also the special severity of DFATAL, which logs FATAL in
 // debug mode, ERROR in normal mode.
 
 namespace logging {
 
-// Where to record logging output? A flat file and/or system debug log via
-// OutputDebugString. Defaults on Windows to LOG_ONLY_TO_FILE, and on
-// POSIX to LOG_ONLY_TO_SYSTEM_DEBUG_LOG (aka stderr).
-enum LoggingDestination { LOG_NONE,
-                          LOG_ONLY_TO_FILE,
-                          LOG_ONLY_TO_SYSTEM_DEBUG_LOG,
-                          LOG_TO_BOTH_FILE_AND_SYSTEM_DEBUG_LOG };
+// TODO(avi): do we want to do a unification of character types here?
+#if defined(OS_WIN)
+typedef wchar_t PathChar;
+#else
+typedef char PathChar;
+#endif
+
+// Where to record logging output? A flat file and/or system debug log
+// via OutputDebugString.
+enum LoggingDestination {
+  LOG_NONE                = 0,
+  LOG_TO_FILE             = 1 << 0,
+  LOG_TO_SYSTEM_DEBUG_LOG = 1 << 1,
+
+  LOG_TO_ALL = LOG_TO_FILE | LOG_TO_SYSTEM_DEBUG_LOG,
+
+  // On Windows, use a file next to the exe; on POSIX platforms, where
+  // it may not even be possible to locate the executable on disk, use
+  // stderr.
+#if defined(OS_WIN)
+  LOG_DEFAULT = LOG_TO_FILE,
+#elif defined(OS_POSIX)
+  LOG_DEFAULT = LOG_TO_SYSTEM_DEBUG_LOG,
+#endif
+};
 
 // Indicates that the log file should be locked when being written to.
-// Often, there is no locking, which is fine for a single threaded program.
-// If logging is being done from multiple threads or there can be more than
-// one process doing the logging, the file should be locked during writes to
-// make each log outut atomic. Other writers will block.
+// Unless there is only one single-threaded process that is logging to
+// the log file, the file should be locked during writes to make each
+// log outut atomic. Other writers will block.
 //
 // All processes writing to the log file must have their locking set for it to
-// work properly. Defaults to DONT_LOCK_LOG_FILE.
+// work properly. Defaults to LOCK_LOG_FILE.
 enum LogLockingState { LOCK_LOG_FILE, DONT_LOCK_LOG_FILE };
 
 // On startup, should we delete or append to an existing log file (if any)?
 // Defaults to APPEND_TO_OLD_LOG_FILE.
 enum OldFileDeletionState { DELETE_OLD_LOG_FILE, APPEND_TO_OLD_LOG_FILE };
 
 enum DcheckState {
   DISABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS,
   ENABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS
 };
 
-// TODO(avi): do we want to do a unification of character types here?
-#if defined(OS_WIN)
-typedef wchar_t PathChar;
-#else
-typedef char PathChar;
-#endif
+struct BASE_EXPORT LoggingSettings {
+  // The defaults values are:
+  //
+  //  logging_dest: LOG_DEFAULT
+  //  log_file:     NULL
+  //  lock_log:     LOCK_LOG_FILE
+  //  delete_old:   APPEND_TO_OLD_LOG_FILE
+  //  dcheck_state: DISABLE_DCHECK_FOR_NON_OFFICIAL_RELEASE_BUILDS
+  LoggingSettings();
+
+  LoggingDestination logging_dest;
+
+  // The three settings below have an effect only when LOG_TO_FILE is
+  // set in |logging_dest|.
+  const PathChar* log_file;
+  LogLockingState lock_log;
+  OldFileDeletionState delete_old;
+
+  DcheckState dcheck_state;
+};
 
 // Define different names for the BaseInitLoggingImpl() function depending on
 // whether NDEBUG is defined or not so that we'll fail to link if someone tries
 // to compile logging.cc with NDEBUG but includes logging.h without defining it,
 // or vice versa.
 #if NDEBUG
 #define BaseInitLoggingImpl BaseInitLoggingImpl_built_with_NDEBUG
 #else
 #define BaseInitLoggingImpl BaseInitLoggingImpl_built_without_NDEBUG
 #endif
 
 // Implementation of the InitLogging() method declared below.  We use a
 // more-specific name so we can #define it above without affecting other code
 // that has named stuff "InitLogging".
-BASE_EXPORT bool BaseInitLoggingImpl(const PathChar* log_file,
-                                     LoggingDestination logging_dest,
-                                     LogLockingState lock_log,
-                                     OldFileDeletionState delete_old,
-                                     DcheckState dcheck_state);
+BASE_EXPORT bool BaseInitLoggingImpl(const LoggingSettings& settings);
 
 // Sets the log file name and other global logging state. Calling this function
 // is recommended, and is normally done at the beginning of application init.
 // If you don't call it, all the flags will be initialized to their default
 // values, and there is a race condition that may leak a critical section
 // object if two threads try to do the first log at the same time.
 // See the definition of the enums above for descriptions and default values.
 //
 // The default log file is initialized to "debug.log" in the application
 // directory. You probably don't want this, especially since the program
 // directory may not be writable on an enduser's system.
 //
 // This function may be called a second time to re-direct logging (e.g after
 // loging in to a user partition), however it should never be called more than
 // twice.
-inline bool InitLogging(const PathChar* log_file,
-                        LoggingDestination logging_dest,
-                        LogLockingState lock_log,
-                        OldFileDeletionState delete_old,
-                        DcheckState dcheck_state) {
-  return BaseInitLoggingImpl(log_file, logging_dest, lock_log,
-                             delete_old, dcheck_state);
+inline bool InitLogging(const LoggingSettings& settings) {
+  return BaseInitLoggingImpl(settings);
 }
 
 // Sets the log level. Anything at or above this level will be written to the
 // log file/displayed to the user (if applicable). Anything below this level
 // will be silently ignored. The log level defaults to 0 (everything is logged
 // up to level INFO) if this function is not called.
 // Note that log messages for VLOG(x) are logged at level -x, so setting
 // the min log level to negative values enables verbose logging.
 BASE_EXPORT void SetMinLogLevel(int level);
 
@@ skipping 758 matching lines @@
 #elif NOTIMPLEMENTED_POLICY == 5
 #define NOTIMPLEMENTED() do {\
   static bool logged_once = false;\
   LOG_IF(ERROR, !logged_once) << NOTIMPLEMENTED_MSG;\
   logged_once = true;\
 } while(0);\
 EAT_STREAM_PARAMETERS
 #endif
 
 #endif  // BASE_LOGGING_H_